Pancreatic ductal adenocarcinoma (PDAC) is one of the most deadly human cancers and in ~95% of cases driven by oncogenic mutations of Kras. Therefore, oncogenic Kras and its downstream effectors are, in theory, ideal candidates for PDAC therapeutic intervention. Unfortunately, attempts to directly inhibit oncogenic Kras or known Ras effector pathways have been either unsuccessful or proven ineffective. As a result, there is significant interest in identifying novel downstream effectors of oncogenic Kras signaling that could be amenable to pharmacological intervention. We have recently identified Yap (Yes-associated-protein) as an essential mediator of oncogenic Kras signaling during PDAC development (manuscript currently under review). In this grant we propose a multi-faceted effort to identify the mechanism through which Yap and its transcriptional partners Tead1/2/3/4 mediate oncogenic Kras signaling and determine whether Yap and Tead1/2/3/4 are required for PDAC maintenance and metastasis. In Aim 1, we will identify the signal transduction events that connect oncogenic Kras to the Yap-Tead transcriptional complex. We will focus on characterizing how oncogenic-Kras-induced posttranscriptional modifications of Yap affects Yap-mediated transcription and PDAC development. In Aim 2, we will determine the requirement for Yap in PDAC tumor maintenance and metastases using orthotopic mouse models engineered to inducibly express Yap shRNAs. These mouse models will validate the potential of Yap as a therapeutic target for PDAC. In Aim 3, we will test the hypothesis that Tead1/2/3/4 function in concert with Yap to mediate the transcription of key oncogenic Kras-induced genes and support PDAC development and progression in vitro and in vivo. Collectively, these proposed studies will provide critical insights into the molecular mechanisms underlying PDAC pathogenesis, opening doors to more effective treatment strategies for PDAC.